As the demand for diesel boiling range fuel and fuel blending components increases worldwide there is increasing interest in sources other than petroleum crude oil for producing diesel boiling range fuel. One such source is what has been termed renewable sources. These renewable sources include, but are not limited to, plant oils such as corn, rapeseed, canola, soybean and algal oils, animal fats such as tallow, fish oils and various waste streams such as yellow and brown greases and sewage sludge. The common feature of these sources is that they are composed of glycerides and Free Fatty Acids (FFA). Both of these classes of compounds contain aliphatic carbon chains having from about 8 to about 24 carbon atoms. The aliphatic carbon chains in the glycerides or FFAs can be saturated or mono-, di- or poly-unsaturated.
There are reports in the art disclosing the production of hydrocarbons from oils. For example, U.S. Pat. No. 4,300,009 discloses the use of crystalline aluminosilicate zeolites to convert plant oils such as corn oil to hydrocarbons such as gasoline and chemicals such as paraxylene. U.S. Pat. No. 4,992,605 discloses the production of hydrocarbon products in the diesel boiling range by hydroprocessing vegetable oils such as canola or sunflower oil. Finally, US 2004/0230085 A1 discloses a process for treating a hydrocarbon component of biological origin by hydrodeoxygenation followed by isomerization.
Applicants have developed a process which comprises one or more steps to hydrogenate, decarboxylate, decarbonylate, (and/or hydrodeoxygenate) and isomerize the renewable feedstock. The consumption of hydrogen in the deoxygenation reaction zone is reduced by driving more of the conversion to occur through decarboxylation and decarbonylation which, unlike hydrogenation and hydrodeoxygenation, does not consume hydrogen. At least one sulfur containing component is added in an amount sufficient to increase the amount of decarboxylation and decarbonylation relative to the hydrogenation and hydrodeoxygenation. The sulfur containing component also operates to maintain the catalyst in a sulfided state.